This invention relates to a mobile suspended scaffold arrangement particularly of a type which includes a support portion which can run on rails on the roof of a building with a scaffold portion carried on the support portion and suspended over an edge of the roof to lie along side a wall of the building for carrying out building operations on the wall and in the area of the junction between the wall and the roof.
Various arrangements of scaffold arrangement of this type have previously been proposed and in a search carried out in relation to the present invention the following U.S. patents were revealed: U.S. Pat. Nos. 3,854,550 - 2,639,950 - 1,054,376 3,245,355 - 3,066,757 - 3,454,818 - 4,074,789 and 3,282,377.
Of these prior patents probably the most relevant are U.S. Pat. No. 3,854,550 (Shingler) issued in 1974 and U.S. Pat. No. 4,074,789 (Warren et al) issued in 1978. The second of these patents shows a device which is arranged for rolling movement along the Z-shaped purlins of a building under construction. This patent shows a rolling arrangement on the purlins which includes what the inventor calls "force rollers" which run along the underside surface of a purlin to prevent the device toppling from the roof. Such an arrangement has a significant disadvantage in that it is difficult to apply to the rails or purlins and furthermore it is not suitable for use with rails or purlins of a different shape without significant modification.
The Shingler patent shows a device which runs on specifically mounted planks and uses a counterweight arrangement. However the construction of the wheel arrangement is not satisfactory for use on rails of different shapes and the unit is limited therefore in its use.
There remains therefore a requirement for a mobile scaffold of this type which is designed particularly but not exclusively for use in the assembly of steel buildings. According to a first aspect of the invention, therefore, there is provided a mobile suspended scaffold arrangement comprising a support portion for running along a roof of a building and a scaffold portion arranged to be suspended from said support portion along a side wall of the building, said support portion comprising a first wheel assembly for running along a first rail adjacent an edge of the roof, a second wheel assembly for running along a second rail parallel to the first and spaced on the edge of the roof, frame means interconnecting the first and second wheel assemblies so that the support portion forms a platform, each of said wheel assemblies comprising a first and second support wheel spaced longitudinally of the respective rail and each mounted for rotation about an axis parallel to the roof and having a periphery arranged to run on an upper surface parallel to the roof of the respective rail, a first and a second guide wheel spaced longitudinally of the respective rail and mounted for rotation about an axis at right angles to the roof and having a periphery arranged to engage a surface at right angles to the roof of the respective rail, edges of the periphery of the guide wheels being spaced on opposed sides of a plane containing the points of contact between the periphery of the support wheels and the upper surface of the rail, and a counterweight means on said support portion spaced from said first wheel assembly on the side thereof remote from said scaffold portion and arranged to provide sufficient moment about said first wheel assembly to maintain said support wheels of said second wheel assembly in contact with said second rail.
This aspect of the invention therefore provides a particular form of wheel arrangement which cooperates with the counterweight so that the support portion can readily be mounted upon the roof of the building and is readily adjustable to suit different rail or purlin arrangements. The wheel arrangements using the support wheels and the guide wheels arranged at right angles thereto enable the device to run on various shapes of rail without the necessity for modification or adjustment.
According to a second aspect of the invention there is provided a mobile suspended scaffold arrangement comprising a support portion for running along a roof of a building and a scaffold portion arranged to be suspended from said support portion along a side wall of the building, said support portion comprising a first wheel assembly for running along a first rail adjacent an edge of the roof, a second wheel assembly for running along a second rail parallel to the first and spaced on the edge of the roof, frame means interconnecting the first and second wheel assemblies so that the support portion forms a platform, said support portion comprising a pair of first wheel assemblies and a pair of second wheel assemblies and a pair of frame means each interconnecting a respective one of the pairs of first and second wheel assemblies thus forming two separate dollies movable separately along the roof on said first and second rails and means for connecting said first and second dollies to form an integral support portion for said scaffold portion.
This aspect therefore provides an improved construction of the support portion which enables it to operate not only as a support for the scaffold portion but also to form a pair of dollies which can be used in carrying roof panels for use in the cladding of the roof in the conventional steel building construction. Preferably the dollies are formed by splitting the support portion in the form of a platform into two separate halves in a direction at right angles to the rails so that two halves can continue to run on the rails and each half can be used to carry various pieces of equipment used in the roof cladding process.
According to a third aspect of the invention there is provided a mobile suspended scaffold arrangement comprising a support portion for running along a roof of a building and a scaffold portion arranged to be suspended from said support portion along a side wall of the building, said support portion comprising a first wheel assembly for running along a first rail adjacent an edge of the roof, a second wheel assembly for running along a second rail parallel to the first and spaced on the edge of the roof, frame means interconnecting the first and second wheel assemblies so that the support portion forms a platform, said scaffold portion comprising a pair of rigid suspension members each supported from said support portion at a position spaced therealong longitudinally of said rail, each of said suspension members being attached to said support portion at two positions thereon spaced in a plane lying at right angles to the rail whereby the suspension members are held rigid relative to said support portion.
This aspect therefore provides an improved connection between the scaffold portion and the support portion so that the scaffold portion is held rigid as opposed to the conventional swinging cable supported scaffold portions of the prior art. This arrangement enables the device to operate most effectively for its intended purpose of supporting an operative suitably at a position adjacent the wall or junction between the wall and the roof so that he can operate upon the part for cladding or other operations as required while being supported in a manner which allows movements and forces to be applied without the scaffold portion swinging about.